Patch 5.4.0 (10-Sep-2013) Psyfiend no longer benefits from Haste, and its health has been reduced by 75%, but fixed a bug where Psyfiend wasn't being affected by base Resilience.

Patch 5.2.0 (5-Mar-2013): Psyfiend belonging to an individual Priest will no longer cast Psychic Horror on the same target twice.

Patch 5.1.0 (27-Nov-2012): Psyfiend's Psychic Terror cast time has been increased to 2 seconds, up from 1.5 seconds.; The Psyfiend's health has been reduced to 10% of the controlling Priest's health, down from 30%.